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Transcranial Theta-Burst Stimulation

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Transcranial magnetic stimulation (TMS) has already been described in section 2.6.  Transcranial theta-burst stimulation (TBS) differs from TMS in that the stimulation includes patterned (vs non-patterned in repetitive TMS) bursts of shorter duration pulses.  Conceptually, intermittent TBS (iTBS, Martin JH 2016; Huang YZ et al 2005) may produce a more robust strengthening of synaptic activity in residual neural pathways.

Table: Studies of TBS for Reducing Spasticity

Discussion

Intermittent theta-burst stimulation is a new intervention being applied to people with incomplete cervical SCI to potentially improve upper limb spasticity, pain and sensorimotor function. Gharooni et al (2018; RCT) administered a total of 600 pulses in 200 seconds 3 stimuli at 50Hz, repeated at 200 ms intervals for 2 seconds and interspersed by 8 seconds between pulse trains).  Sham iTBS was the same except with the stimulation coil rotated 90° from the participants midline axis to ensure no brain stimulation. Sessions of iTBS (or sham iTBS) were delivered 10 times over 2 weeks with a 2-week washout period before crossover to the alternative intervention. Three spasticity outcome assessments (modified Ashworth Scale (MAS), Leeds Arm Spasticity Impact Scale (LASIS) and a Visual Analogue Scale for spasticity (VAS-S)) were applied to bilateral elbow and wrist extension and flexion.  Results were reported to support a non-significant reduction in MAS compared to sham iTBS and that were not of a magnitude that could be perceived by participants as improved function (via VAS-S and LASIS).

Nardone et al (2017), using SCAT (Spinal Cord Assessment Tool for Spasticity) and MAS and a stimulation protocol as described above (Gharooni et al 2018) with the exception that the washout period was 2 months (vs 2 weeks), found a significant reduction of upper extremity spasticity (p<0.001 for both SCAT and MAS) that returned to baseline within one week.

Conclusions

There is level 1b evidence (Nardone et al 2017; RCT) that iTBS reduces upper extremity spasticity for up to 1 week.

  • Treatment with intermittant theta-burst stimulation is likely to reduce upper extremity spasticity for up to 1 week.